After excluding the patients with PAD, the HO-1 levels were significantly higher in the patients with CAD than in those without CAD (0.45 versus 0.35 ng/mL, p < 0.05) and were highest in the patients with one-vessel disease among the four groups of CAD(-), one-vessel (1-VD), two-vessel (2-VD), and three-vessel disease (3-VD) (0.35, 0.49, 0.44, and 0.44 ng/mL, p < 0.05) (Figure 3). Here, HMOX1 is linked to peripheral arterial disease.